The present invention relates that to a wrench mountable on a frame for movement under power between an out of the way datum position to a position adjacent to a pipe or drill rod and thereafter move at least one wrench jaw from an unclamped rod position to a rod clamping position.
In U.S. Pat. No. 3,994,350 to Smith et al there is disclosed a drill rig frame on which one end of a hydraulic cylinder is pivotally mounted and its piston rod pivotally connected to a shaft to pivot the shaft and thereby a wrench between a position aligned with a bore hole and a position out of the aligned position, and a second cylinder pivotally mounted on the wrench arm and pivotally connected to wrench jaw for moving the jaw from a rod clamped to a rod unclamped position (see FIGS. 9 and 10 of the patent).
Each of U.S. Pat. Nos. 4,475,604 to Albertson; 4,345,439 to Rassieur and 3,985,189 to Jahnke disclose a pipe wrench having its fixed jaw member one end pivotally connected to a piston cylinder combination for being moved thereby and an adjustable jaw mounted on the fixed jaw for being adjustable relative to the fixed jaw by rotating the wrench nut.
U.S. Pat. No. 4,721,171 to Leppanen discloses a first piston cylinder combination for moving one jaw relative to another between rod clamping and unclamping positions and a second piston cylinder combination for moving the jaw mount between two spaced positions, one of which is aligned with the rod.
The present apparatus is directed to making improvements in wrench apparatus such as disclosed in the above mentioned patents and to overcome dangerous conditions associated with the use of manually held and/or moved wrenches used during rod joint breaking operations.